I've been wondering around trying to find something for my setting. I've bought a set of Eagle Arion 2.1 Speakers. They sould awesome and all but... there is one thing : I don't have an headphone 3.5mm jack on either the speakers or the sub.

Since I want to both use my heaphones (night) and speakers (day), is their a cord that could let me use both without me going behind my PC and plug my headphones directly on the soundcard?

And, if possible, I would like to enjoy the improvement I can give to my sound that my speakers gives me (bass & treble ajustment).

So you'd have your speakers into one portion of the splitter, and that cable into the other running up to your desk. Then just plug the headphones into that when you want to use them. I use one of those splitters for my PC speakers and my stereo system and it works well.